The reason for closed practices is that you don't want 20 sets of parents, with 20 different opinions, second guessing your every move. Do you want 20 people coming into your place of employment and telling you how to perform your job?
The coach was hired to do a job, if you don't like the way he/she coaches, your DD doesn't have to participate. She doesn't have a god given right to play school ball.
I don't agree. As part of any job, you need to listen. Listening and learning are part of growth and any self respecting coach at any level should want to grow. The don't have to agree or implement, but they should listen. 20 opinions are just that and it is up to the coach to decide if any are opinions are valid or not. No coach should mandate that no one speak with them about an issue - perceived or not.
Say a coach believed in something yet someone could offer a persuasive argument, video proof, ..etc that they may be wrong. Should they ignore it and stick with their belief simply because they are the coach?
If I have an employee who is not willing to listen to alternate ideas in the event they may learn something, then that employee will not be with me long at all.
My DD is in 7th grade, so I don't have a dog in this fight.